Direct methanol fuel cells are usually fed by atmospheric air on the cathode side of the membrane and methanol diluted in water on the anode side of the membrane. When large amounts of methanol are provided to the anode side of the membrane, the methanol may pass through the membrane and be oxidized at the cathode side of the membrane. This process results in wasting of methanol and also results in loss of cell voltage by unwanted cathode side reaction of methanol. There remains a need for better ways to regulate the concentration of fuel in a fuel cell to provide better fuel cell performance.